Gao Shuangcheng, Gu Yong Qiang, Wu Jiajie, Coleman-Derr Devin, Huo Naxin, Crossman Curt, Jia Jizeng, Zuo Qi, Ren Zhenglong, Anderson Olin D, Kong Xiuying
Key Laboratory of Crop Germplasm & Biotechnology, MOA, Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, National Key Facility for Crop Gene Resources and Genetic Improvement, Zhongguancun, Beijing, PR China.
Plant Mol Biol. 2007 Sep;65(1-2):189-203. doi: 10.1007/s11103-007-9208-1. Epub 2007 Jul 16.
Genes encoding wheat prolamins belong to complicated multi-gene families in the wheat genome. To understand the structural complexity of storage protein loci, we sequenced and analyzed orthologous regions containing both gliadin and LMW-glutenin genes from the A and B genomes of a tetraploid wheat species, Triticum turgidum ssp. durum. Despite their physical proximity to one another, the gliadin genes and LMW-glutenin genes are organized quite differently. The gliadin genes are found to be more clustered than the LMW-glutenin genes which are separated from each other by much larger distances. The separation of the LMW-glutenin genes is the result of both the insertion of large blocks of repetitive DNA owing to the rapid amplification of retrotransposons and the presence of genetic loci interspersed between them. Sequence comparisons of the orthologous regions reveal that gene movement could be one of the major factors contributing to the violation of microcolinearity between the homoeologous A and B genomes in wheat. The rapid sequence rearrangements and differential insertion of repetitive DNA has caused the gene islands to be not conserved in compared regions. In addition, we demonstrated that the i-type LMW-glutenin originated from a deletion of 33-bps in the 5' coding region of the m-type gene. Our results show that multiple rounds of segmental duplication of prolamin genes have driven the amplification of the omega-gliadin genes in the region; such segmental duplication could greatly increase the repetitive DNA content in the genome depending on the amount of repetitive DNA present in the original duplicate region.
编码小麦醇溶蛋白的基因属于小麦基因组中复杂的多基因家族。为了解贮藏蛋白基因座的结构复杂性，我们对四倍体小麦物种普通小麦（Triticum turgidum ssp. durum）A和B基因组中包含醇溶蛋白和低分子量麦谷蛋白基因的直系同源区域进行了测序和分析。尽管醇溶蛋白基因和低分子量麦谷蛋白基因在物理位置上彼此相邻，但它们的组织方式却大不相同。醇溶蛋白基因比低分子量麦谷蛋白基因聚类程度更高，低分子量麦谷蛋白基因彼此之间的距离要大得多。低分子量麦谷蛋白基因的分离是由于逆转座子的快速扩增导致大片段重复DNA插入以及其间散布的基因座存在的结果。直系同源区域的序列比较表明，基因移动可能是导致小麦A和B同源基因组之间微观共线性破坏的主要因素之一。快速的序列重排和重复DNA的差异插入导致比较区域中的基因岛不保守。此外，我们证明了i型低分子量麦谷蛋白起源于m型基因5'编码区33个碱基对的缺失。我们的结果表明，醇溶蛋白基因的多轮片段重复驱动了该区域ω-醇溶蛋白基因的扩增；这种片段重复可能会根据原始重复区域中存在的重复DNA量极大地增加基因组中的重复DNA含量。
